An oligopeptide, is a peptide consisting of two to twenty amino acids, including dipeptides, tripeptides, tetrapeptides, and other polypeptides. Some of the major classes of naturally occurring oligopeptides include aeruginosins, cyanopeptolins, microcystins, microviridins, microginins, anabaenopeptins, and cyclamides. Microcystins are best studied because of their potential toxicity impact in drinking water. A review of some oligopeptides found that the largest class are the cyanopeptolins (40.1%), followed by microcystins (13.4%).
A dipeptide is an organic compound derived from two amino acids. The constituent amino acids can be the same or different. When different, two isomers of the dipeptide are possible, depending on the sequence. Several dipeptides are physiologically important, and some are both physiologically and commercially significant. A well known dipeptide is aspartame, an artificial sweetener.
Ranpirnase is a ribonuclease enzyme found in the oocytes of the Northern Leopard Frog. Ranpirnase is a member of the pancreatic ribonuclease protein superfamily and degrades RNA substrates with a sequence preference for uracil and guanine nucleotides. Along with amphinase, another leopard frog ribonuclease, Ranpirnase has been studied as a potential cancer and antiviral treatment due to its unusual mechanism of cytotoxicity tested against transformed cells and antiviral activity.
Calciseptine (CaS) is a natural neurotoxin isolated from the black mamba Dendroaspis p. polylepis venom. This toxin consists of 60 amino acids with four disulfide bonds. Calciseptine specifically blocks L-type calcium channels, but not other voltage-dependent Ca2+ channels such as N-type and T-type channels.
The PDE2 enzyme is one of 21 different phosphodiesterases (PDE) found in mammals. These different PDEs can be subdivided to 11 families. The different PDEs of the same family are functionally related despite the fact that their amino acid sequences show considerable divergence. The PDEs have different substrate specificities. Some are cAMP selective hydrolases, others are cGMP selective hydrolases and the rest can hydrolyse both cAMP and cGMP.
Salinosporamide A (Marizomib) is a potent proteasome inhibitor being studied as a potential anticancer agent. It entered phase I human clinical trials for the treatment of multiple myeloma, only three years after its discovery in 2003. This marine natural product is produced by the obligate marine bacteria Salinispora tropica and Salinispora arenicola, which are found in ocean sediment. Salinosporamide A belongs to a family of compounds, known collectively as salinosporamides, which possess a densely functionalized γ-lactam-β-lactone bicyclic core.
A mitotic inhibitor, microtubule inhibitor, or tubulin inhibitor, is a drug that inhibits mitosis, or cell division, and is used in treating cancer, gout, and nail fungus. These drugs disrupt microtubules, which are structures that pull the chromosomes apart when a cell divides. Mitotic inhibitors are used in cancer treatment, because cancer cells are able to grow through continuous division that eventually spread through the body (metastasize). Thus, cancer cells are more sensitive to inhibition of mitosis than normal cells. Mitotic inhibitors are also used in cytogenetics, where they stop cell division at a stage where chromosomes can be easily examined.
Cecropins are antimicrobial peptides. They were first isolated from the hemolymph of Hyalophora cecropia, whence the term cecropin was derived. Cecropins lyse bacterial cell membranes; they also inhibit proline uptake and cause leaky membranes.
Xestospongia testudinaria is a species of barrel sponge in the family Petrosiidae. More commonly known as Giant Barrel Sponges, they have the basic structure of a typical sponge. Their body is made of a reticulation of cells aggregate on a siliceous scaffold composed of small spikes called spicules. Water is taken into the inner chamber of the sponge through ostia. Flagellated choanocytes line the inner chamber and help generate water currents through the sponge.
Patellamide A is a peptide natural product produced by Prochloron didemni, a cyanobacterial symbiont of Lissoclinum patella, and was first isolated in 1981. Patellamide A is one of many didemnid peptides. Other closely related peptides include patellamides B, C, and D and trunkamide. The patellamides and trunkamide show moderate cytotoxicity and activity against multidrug resistant cancer cell lines.
Valorphin, also known as VV-hemorphin-5, is a naturally occurring, endogenous opioid heptapeptide of the hemorphin family with the amino acid sequence H-Val-Val-Tyr-Pro-Trp-Thr-Gln-OH (VVYPWTQ). It is produced in the body via proteolyic cleavage of residues 33-39 of the β-chain of hemoglobin. Valorphin binds preferentially to the μ-opioid receptor and produces effects such as analgesia and self-administration in animals. It also possesses cytotoxic and antiproliferative properties against tumor cells, the mediation of which, because they are reversed by naloxone, appears to be dependent on the opioid receptors.
Lacking an immune system, protective shell, or mobility, sponges have developed an ability to synthesize a variety of unusual compounds for survival. C-nucleosides isolated from Caribbean Cryptotethya crypta, were the basis for the synthesis of zidovudine (AZT), aciclovir (Cyclovir), cytarabine (Depocyt), and cytarabine derivative gemcitabine (Gemzar).
The cyclothiazomycins are a group of natural products, classified as thiopeptides, which are produced by various Streptomyces species of bacteria.
Ssm6a, or μ-SLPTX-Ssm6a, is a toxin from the venom of the Chinese red-headed centipede. It has strong analgesic properties, probably owing to its strong inhibitory effects on Nav1.7 channels.
Kalkitoxin, a toxin derived from the cyanobacterium Lyngbya majuscula, induces NMDA receptor mediated neuronal necrosis, blocks voltage-dependent sodium channels, and induces cellular hypoxia by inhibiting the electron transport chain (ETC) complex 1.
Esculentin-2CHa is an antimicrobial peptide located outside the epithelial cell's membrane of the skin of many species of amphibians, such as Rana chiricahuensis. This peptide has recently become more important due to its defense response function and its possible application in the treatment of various human pathologies, that range from type 2 diabetes to bacterial and fungi infections. Esculentin-2CHa is a peptide that belongs to the Esculentin-2 family, which is known for its broad-spectrum of antimicrobial activity and its low cytotoxicity to human erythrocytes. However, not much is known about its structures and their relation to the functions these peptides carry out.
Carole Ann Bewley is an American chemist. She is a senior investigator and Chief of the Laboratory of Bioorganic Chemistry at the United States National Institute of Diabetes and Digestive and Kidney Diseases. Bewley researches secondary metabolites and basic principles involved in protein-carbohydrate interactions and how these can be exploited to engineer therapeutics.
Avarol is a hydroquinone first isolated from the Mediterranean marine sponge Dysidea avara 1974 Avarol represented the first sesquiterpenoid with a rearranged drimane skeleton and its structure was established by standard analytical methods, chemical degradation and later by stereocontrolled synthesis. Intrigued by the wide range of biological activities of this metabolite, Avarol has inspired the development of many synthetic derivatives and the study of their applications.
Halovir refers to a multi-analogue compound belonging to a group of oligopeptides designated as lipopeptaibols which have membrane-modifying capacity and are fungal in origin. These peptides display interesting microheterogeneity; slight variation in encoding amino acids gives rise to a mixture of closely related analogues and have been shown to have antibacterial/antiviral properties.
Jamaicamide A is a lipopeptide isolated from the cyanobacterium Moorea producens, formerly known as Lyngbya majuscula. Jamaicamide A belongs to a family of compounds collectively called jamaicamides, which are sodium channel blockers with potent neurotoxicity in a cellular model. Jamaicamide A has several unusual functionalities, including an alkynyl bromide, vinyl chloride, β-methoxy eneone system, and pyrrolinone ring.
